Comprehensive evaluation of tillage and straw returning on soil fertility in a wheat-rice double cropping system

An experiment of four treatments (no-tillage + straw mulching, NTS; no-tillage + high stubble remaining, NT; conventional tillage + straw incorporation, CTS and conventional tillage + no straw returning, CK) was designed to investigate the effect of tillage and straw returning on soil fertility in a wheat-rice double cropping system. The experiment was conducted under field condition and micro-plots in isolated concrete ponds for three consecutive years. Results show that no tillage plus straw returning significantly increases the nutrients content of soil organic matter, available P and K, especially for those at the 0～7 cm soil layer. Compared with CK treatment, the NTS and NT increase soil bulk density. The comprehensive evaluation of soil fertility indicates that nutrient fertility index (NFI), is the highest under NTS, and the lowest under CT. However, affected by bulk density, integrated fertility index (IFI) is the highest under CTS treatment, and the lowest under NT treatment. Viewed from layers, IFI and NFI are higher in the upper layer(0～7 cm), lower at 14～21 cm layer, especially for those NTS and NT treatment.